Stress proteins on the yeast cell surface determine resistance to osmotin, a plant antifungal protein

• Published in: Proceedings of the National Academy of Sciences - PNAS 1997-06, Vol.94 (13), p.7082-7087
• Main Authors: Yun, D.J. (Purdue University, West Lafayette, IN.), Zhao, Y, Pardo, J.M, Narasimhan, M.L, Damsz, B, Lee, H, Abad, L.R, D'Urzo, M.P, Hasegawa, P.M, Bressan, R.A
• Format: Article
• Language: English
• Subjects: Antibodies; Antifungals; ATRIPLEX NUMMULARIA; Biological Sciences; Botany; Cell membranes; CELL WALLS; Cellular biology; Cloning, Molecular; DEFENCE MECHANISMS; Drug Resistance, Microbial - genetics; Fungi; Gene Expression Regulation, Fungal; Genes, Fungal; Heat-Shock Proteins - genetics; IMMUNOCYTOCHEMISTRY; IMMUNOLOGIE; IMMUNOLOGY; INMUNOLOGIA; MECANISME DE DEFENSE; MECANISMOS DE DEFENSA; Microscopy, Immunoelectron; MUTACION; MUTATION; NICOTIANA TABACUM; PARED CELULAR; PAROI CELLULAIRE; PATHOGENESE; PATHOGENESIS; PATOGENESIS; Plant Proteins - genetics; Plants; Protein isoforms; PROTEINAS; PROTEINE; PROTEINS; Receptors; SACCHAROMYCES CEREVISIAE; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - growth & development; Saccharomyces cerevisiae - ultrastructure; Spheroplasts; Yeasts
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.94.13.7082

Strains of the yeast Saccharomyces cerevisiae differ in their sensitivities to tobacco osmotin, an antifungal protein of the PR-5 family. However, cells sensitive to tobacco osmotin showed resistance to osmotin-like proteins purified from the plant Atriplex nummularia, indicating a strict specificity between the antifungal protein and its target cell. A member of a gene family encoding stress proteins induced by heat and nitrogen limitation, collectively called Pir proteins, was isolated among the genes that conveyed resistance to tobacco osmotin to a susceptible strain. We show that overexpression of Pir proteins increased resistance to osmotin, whereas simultaneous deletion of all PIR genes in a tolerant strain resulted in sensitivity. Pir proteins have been immunolocalized to the cell wall. The enzymatic digestion of the cell wall of sensitive and resistant cells rendered spheroplasts equally susceptible to the cytotoxic action of tobacco osmotin but not to other osmotin-like proteins, indicating that the cell membrane interacts specifically with osmotin and facilitates its action. Our results demonstrate that fungal cell wall proteins are determinants of resistance to antifungal PR-5 proteins